FIG. 1 illustrates a conventional switch control circuit 102 that controls a charge switch QCHG and a discharge switch QDSG for a battery 138 in a battery pack 100. The control circuit 102 generates driving signals DCHG and DDSG to turn on or off the switches QCHG and QDSG, under control of a microcontroller unit (MCU) 108. For instance, the MCU 108 can instruct the control circuit 102 to turn on the charge switch QCHG such that a charger connected to the terminals PACK+ and PACK− charges the battery 138, or to turn off the charge switch QCHG if the battery 138 is fully charged or an abnormal condition such as over-charge, over-current, or the like occurs. For another instance, the MCU 108 can instruct the control circuit 102 to turn on the discharge switch QDSG such that battery 138 discharges to power a load connected to the terminals PACK+ and PACK−, or to turn off the discharge switch QDSG if an abnormal condition such as over-discharge, over-load, or the like occurs. The MCU 108 can also instruct the control circuit 102 to turn off both the switches QCHG and QDSG such that the battery pack 100 enters into a deep sleep mode or a low-power mode in which the power can be saved.
However, the conventional switch control circuit 102 has some shortcomings. For example, when the charge switch QCHG is off, additional circuitry (not shown) is used to detect whether a charger is connected to the terminals PACK+ and PACK− because the conventional switch control circuit 102 does not perform the detection. Similarly, when the discharge switch QDSG is off, additional circuitry is used to detect whether an above mentioned over-load condition has been removed. Moreover, when the battery 138 is powering a load, additional circuitry is used to detect whether an abnormal condition such as short-circuit load, over-load, or the like occurs. The additional circuitry increases the cost, PCB size, and power consumption of a battery management system for the battery pack 100. Thus, a switch control circuit that not only has the functions of the switch control circuit 102 but also performs the abovementioned detections would be beneficial.